Conventional power plants burn fossil fuels such as coal to generate electrical energy, i.e., electricity. The focus when constructing these power plants is on maximum efficiency in operation, thereby minimizing the amount of waste gas—containing, among other components, the greenhouse gas carbon dioxide-generated for a given output. In operation, nevertheless, large amounts of carbon dioxide are formed, and a search is on for methods to avoid this.
In the case of one such method, called Carbon Capture and Sequestration (CCS), the carbon dioxide is captured and may be pumped into underground reservoirs for eventual, environmentally compatible storage. The energy requirement to achieve this, however, is not insignificant by comparison with the energy yield of the power plant in question.
The fossil-fired power plants, which in many countries, along with atomic power plants, ensure a stable basic supply of energy are contrasted by the power plants which operate with renewable energy sources. These plants do not produce waste gases, but in the case of wind energy and solar energy are unstable and also unpredictable in their energy yield.